Effects of two conjugated linoleic acid isomers on body fat mass in overweight humans.
In this week's edition of Supplement Savvy, I'm going to discuss two products included in many fat loss supplements. First up is conjugated linoleic acid (CLA), a dietary supplement that to my knowledge first began being researched in the 1970's.
However, the primary focus with this supplement was not always with humans and specifically not with regards to our expanding waistlines. In fact, until recently, most of the research was done in rodents.
Albeit, researchers have more recently turned their attention to CLA as a means to reduce body fat, increase fat free mass, improve lipid profiles, act as an anticarcinogen, and as a powerful antioxidant in humans.
With all those promising claims, it appears as if we have a wonder supplement on our hands. Let's take a look at some recent research studies to investigate the claims.
In this study, researchers took two isomers of CLA and measured their effects on body fat mass in overweight humans. As an aside, an isomer describes compounds (in this case CLA) that have the same chemical structure. However, while the basic structure is the same, there may be some specific components of the structure that are not.
While I could get more detailed, I'll leave that out for your benefit. Just know that because of the minor differences in the specific structure, it may have different effects on the body.
The researchers in this study used 81 middle-aged, overweight, healthy men and women to participate in the double-blind, placebo controlled, randomized study. Subjects were given either 3 grams of sunflower oil, 1.5 grams of a specific isomer of CLA, 3 grams of that same isomer, or 1.5 or 3 grams of another isomer (5 total groups in this study) for 18 weeks.
As an aside, three grams is the most commonly recommended dose of CLA even though in our diets, men typically take in approximately 212 mg and women take in 151 mg. Our dietary intake comes primarily from dairy and meat products.
Anyhow, back to the study at hand. Throughout the study subjects came to the lab at predetermined time periods for blood draws, body fat monitoring, anthropometric measurements, dietary analyses, and body weight checks. It's important to note that CLA supplementation was well tolerated.
Moreover, there were no significant changes among the five treatment groups with respect to weight, body mass index, waist-to-hip ratio, percentage of body fat or lean body mass, measured with bioelectrical impedence.
It's also important to note that there were no significant changes in dietary energy intake, which would independently affect weight loss.
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However, if you do happen to have 4 legs, a tail, whiskers and really crave cheese, CLA may be for you.
Source:
Obesity Research, 12(4), 2004
Malpuech-Brugere et al.
Efficacy of a green tea extract rich in catechin Polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.
So while on the topic of fat loss supplements, let's take a look at another ingredient that's recently been included in many of the "ephedra-free" products: green tea extract. Green tea extract is purported to enhance thermogenesis and enhance satiety.
This study was only a 24-hour study and it measured energy expenditure and fat oxidation in humans. Subjects were given either 270 mg of green tea extract (90 mg, 3 times/day), 150 mg of caffeine (50 mg, 3 times/day) or a placebo.
Subjects in the group supplemented with green tea extract had a significant 4% increase in resting metabolic rate and a significant decrease in something called respiratory quotient (which means they were using more fat as fuel).
This increase in metabolic rate did not correlate to any weight or fat loss; however, keep in mind that it was only a 24-hour study. The question remains, though, would this increase continue over a longer period of time or would it be a transient increase that the body grows accustomed to? Only time will tell as more research needs to be conducted.
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It's also important to note that green tea as a beverage also comes with a number of health benefits. Therefore, barring any physical limitations that may be negatively effected by green tea consumption (e.g., any type of blood thinner) it should no doubt be consumed on a regular basis.
Moreover, a recent study showed that those who drank more tea (green, black or oolong) had a lower body weight and lower body fat than those who did not. So drink and continue to make green tea the 2nd most popular beverage consumed in the world--second only to water.
Source:
AJCN 1999;70:1040-1045.
Dulloo et al.